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Dodge Dakota Vibration

tjfitztjfitz Posts: 41
edited August 2014 in Dodge
My daughter's 1990 Dodge Dakota with the 3.9 L engine and automatic transmission with overdrive has developed a vibration. It happens when accelerating while in gear. If the gear selector is set to neutral while rolling, and the engine rpm is speeded up, the vibration doesn't occur.

The vibration appears to me to be coming from the front of the pickup. The Haynes manual gives several possible causes, all related to the transmission or the drive shafts.

Has anyone else experienced this vibration?


  • dustykdustyk Posts: 2,926
    So would you say that the vibration occurs while the engine is under load? Does the vibration increase the more you try to accelerate?

  • Yes, it seems to be under load that the vibration happens.

    I was under the hood again yesterday and found that disconnecting the EGR valve from its vacuum source made the engine run smoother. (The pipe from the exhaust back to the engine has broken off at a weld and maybe had been causing rough-running. Also the engine would idle slower and eventually shut off when coming to a stop, but with the valve disconnected, that problem ended.)

    I took the pickup out for a spin and it ran well until I got to about 35 mph then the vibration began as before. It gets so loud in the cabin that you can hardly hear a passenger talk, and seems to me to be coming from "up front" rather than "from the rear". My daughter just speeds up and finds the noise isn't so bothersome at higher speeds!

    Anyway, I found that shifting the automatic transmission to second seemed to make the vibration less severe, although still there at 35 mph. Going to low or first seemed to stop the vibration entirely, although I wasn't going 35 mph in first. Putting the transmission into neutral and racing the engine to 3000 rpm doesn't produce a vibration, and there is no vibration when rolling down a hill at 35 mph in neutral.

    All that made me suspect that engine or transmission load is causing the vibration, but I don't know what to look for next. I'm hoping it isn't something complex like a transmission bearing or a seal.

    (I checked all the spark plugs and they were clean and correctly gapped and the wiring from the distributor seems secure. This is a throttle body fuel-injected 3.9 L engine.)
  • dustykdustyk Posts: 2,926
    This problem could be caused by a number of things. The easiest and most logical things first, like plug wires, rotor, and distributor cap, regardless how they look to the eye.

  • Thanks for the replies, Dusty. I'll go out and pull off the distributor cap and the rotor and have a look. Unfortunately a cold front hit North Dakota today and I may have to wait a day (no garage).
  • dustykdustyk Posts: 2,926
    A short story. My son had a '91 Dakota, 3.9 motor and 5-speed manual. At about 70,000 he started have performance issues in the form of a heavy miss at speed. We could also hear a back fire through the throttle body occasionally. He was convinced that it was a burnt valve.

    After doing a complete tune-up (plugs, wires, cap & rotor) it seemed to run fine for some time, then started to do the same thing. There were three occasions when he couldn't even get the thing started.

    Well, he was about to tear the engine apart, convinced that the timing chain was bad (he was listening to all of his Chevy friends), or a bad camshaft or bad valves. I was not convinced, however. Having his truck one day I went and got and installed new Mopar plug wires, cap, and rotor and that Dakota ran for another four years and 75,000 miles before needing another full tune-up.

    In that vintage especially the Power Train Computers were highly susceptible to disruption from random electrical impulses brought about by misfiring caused by poor ignition components.

    By the way, that '91 Dak is still on the road and has more than 400,000 miles on it (No tear down!).

    Best regards,
  • Dusty, sorry I didn't come back to the forum before tonight. That last note is very encouraging and I think I'll go forth and do likewise with the cap, rotor and wires!

    I took the cap and rotor and wires off and the rotor metal looked pretty rough. The contacts inside the distributor cap were what I'd call delaminated, with flaking metal. The wires seemed OK, but who knows?

    I put it all back together, and the engine started, but I can't road test it because I'm going to have to replace one of the metal brake lines after a leak developed at the "combination differential and metering valve" (name in my Haynes manual). I thought tightening the flare nut might help, but instead the leak got worse and I am hoping it is just the tubing flare inside the nut that failed and not the very pricey valve.
  • I installed new Mopar distributor cap, rotor and spark plugs wires.

    Then after some struggles I got the new long metal brake line installed. In the process I had to lower the fuel tank to get at some of the old line's hangers and in moving the filler hose I broke the plastic of the filler line housing and had to scout around in a junk yard today for another one. That was installed and all well. The bleeding of the brake lines for air went well, too, although I now have two alarms on the dashboard illuminated continuously: "ABS brakes" and "P Brake". I may have to continue bleeding the system because the brake fluid was dirty.

    I took the pickup out for a spin anyway and found the vibration under load is still there at about 35 mph in drive. In second it also vibrates at 35 mph although at a higher rpm. Shifting into neutral at that speed eliminates the vibration. Revving to high rpm in neutral doesn't cause the vibration.

    During the test drive, the rpm gauge began sticking and only gentle hammering on the dash would make it move. (The pickup seems to have a death wish!)

    The idle is very rough and the engine dies at idle unless I disconnect the vacuum line to the EGR valve.

    Using the ignition switch, I switched the ignition on and off three times and then left it on the fourth time and got these codes: 12, 12, 13, 14, 14. The information I can find seems to say those codes relate to the MAP or maniford absolute pressure sensor.
  • tjfitztjfitz Posts: 41
    I neglected to bleed the "hydraulic valve" on the drivers side above the rear axle. When that got done, the warning lights went out. Brakes are now good. This pickup has rear wheel antilock only.
  • tjfitztjfitz Posts: 41
    Yesterday I backed the pickup down the driveway, and as I shifted from park into reverse, there was a distinct "clank".

    Somewhere in the recesses of memory I recalled that clanking and vibration can be symptoms of a bad universal joint on the driveshaft. This morning I got up early, raised the rear tires off the pavement, supporting the rear axle with two stands and went to work trying to moving the u-joints. I have never done this before, but from what I read, any "give" at all might mean a bad joint, and the rear joint had give. I eventually got the rear joint disconnected from the differential and lowered it then pulled the front of the driveshaft out from the transmission, forgetting that transmission oil would be gushing forth, which it did, all over the driveway before I was able to get one of my wife's cooking pots under the stream.

    As far as I could see, there were no needle bearings left in the rear joint, so I took shaft and all to a local parts dealer/machine shop and they removed the joints and installed new ones. I put the shaft back into the pickup and added what I think was enough new transmission fluid then took the pickup out on the road.

    There was no more clank on shifting, and absolutely no more vibration even going as fast as 60 mph. The pickup now runs like a dream.

    When I asked my daughter how long the pickup had been vibrating before, she said about a year, and her sister had the same problem before she handed the pickup over to her! (That was the first I'd heard of it.)

    I think the brake line mentioned in an earlier posting in this thread probably failed by vibration fatigue. Also, my daughter drove the pickup from Idaho to North Dakota when she returned home about two weeks ago and about 50 miles from home stopped to rest and the pickup wouldn't re-start. She had to get roadside assistance at about 11 pm from a tow-truck and the driver found that the starter was hanging onto the engine by one loose bolt. I'd say the bolts had probably vibrated loose.

    "For want of a nail... ."
  • jslack05jslack05 Posts: 2
    My 1989 Chevy Blazer has the exact same problem and I believe the u-joint may be the solution. how much did it cost you to have it repaired?
  • tjfitztjfitz Posts: 41
    jslack05, I think the two u-joints (front at the transmission output and rear at the differential) cost about $15 each. I brought the drive shaft with its u-joints to the local machine shop that is attached to the parts dealer. I think it cost $45 to pull the old u-joints and press the new ones on. So that probably makes a total of about $75. Usually I keep all the receipts for any work on my pickup, but I can't find the receipts for this work. Sorry I can't give you better info.
  • jslack05jslack05 Posts: 2
    ok that sound reasonable, i'm sure it will cost a bit more for me cause i'll need to take it to a mechanic since i don't have the tools to do it myself but thank you for the valuable information.
  • Have a vibration at 1100-1500 rpm, slight throttle pressure, only in overdrive lock-up, 35-50 mph. Have replaced muffler, resonator, tailpipe, and torque converter - nothing changed. Sounds like exhaust system, but dealer has extensively checked. Any suggestions?
  • Disregard. Sold truck after drivetrain lockup.
  • apobapob Posts: 2
    i am experirencing a vibration at approx 15 mph, that gets much worse approching 55 mph, but then is not so bad on highway speeds, notincing vibration in the steering column, the cab, and odd sounds froms the exhaust,
    any ideas what could cause this?
  • i have a 2002 4wd 3.9 xcab has developed a vibration at highway speeds that sounds like a growling noise and starts pulling to the left....i figured it was a lf wheel bearing... i replaced the lf bearing but did not solve the is hard to hear any noise or play in the front end while jacked up or at low speeds(it does have a slight pull to left at low speeds) the truck only has 50k never been off roading...only use 4wd in the snow....any ideas before i bring to dealer and get bent over??
  • tjfitztjfitz Posts: 41
    Maybe this is no help, but last year, I noticed a growling noise like you describe, and went to several mechanics who all said it was probably a bad front wheel bearings, so I replaced them all. No improvement.

    Then I went to another garage, and the mechanic said it was the differential (my pickup is a 2 wheel-drive 1990) and he showed me that when he popped a rubber stopper from the differential case, put a screwdriver into the oil and took it out, the oil seemed to have very fine metal particles suspended in it. He said it could be the carrier bearings. I had no idea what a carrier bearing was at the time.

    After much worry, I opened the differential cover and somehow got the big ring gear and its associated carrier bearings out, and sure-enough, the bearings were shot.

    I bought new bearings, and removed the old ones, and installed the new ones (I can't remember if the carrier bearings had to be removed and pressed-on by a machine shop -- I find that pain has no memory), put the whole mess back in, did my best to adjust gear "lash", replaced the rear axle bearings, replaced the differential cover, put in synthetic oil, and the growling noise was gone.

    It probably took me a month to get from the point of going to mechanics to ask about the noise to getting the pickup back on the road. Luckily, I have other transportation.
  • thank you very much for the info,,that would make sense,,i think i will check both front and rear differentials to see if there is any metal in the gear oil,,,the only thing that makes me wonder is that i have a pull to the left also while driving at highway speeds
  • tjfitztjfitz Posts: 41
    I don't know if differential problems could cause steering pull, but maybe? It seemed to me, when I had my pickup's rear wheels up on stands and the differential cover off, that turning either wheel alone caused the differential's planetary gears to rotate and the other wheel to turn backwards. If I had the engine running and the transmission in gear, I could probably have watched what happened to the differential when both wheels were turning and I put a drag on one of them. Being a devout coward, I didn't do that.

    I just found a fascinating video that dates from the 1930s, and really gets into the basics of the differential. If you start it at 1 minute 50 seconds, you can cut-out a long sequence of motorcycle cops doing acrobatics in formation! ial/

    There's a good Internet site that names many possible causes for steering pull at
  • tjfitztjfitz Posts: 41
    There is a hyphen or dash in that URL for the differential that shouldn't have been there. Sorry. The correct URL is ial/
  • I Have a 2000 Dakota Quad Cab, 4.7L 4X4 120500 miles.

    In my earlier post the advice I was given by the dealer and one transmission shop was that my torque converter was slipping during interlock. The problem was more noticeable after my tires got balanced. When truck in neutral or at 35-50 mph, slight vibration. Now in an attempt to get a third opinion, one shop advised that I have a clogged fuel injector. They claimed computer showed, pass side bank was running a little rich. He concluded the torque converter was not bad after getting the truck to breakdown or sputter without the interlock engaged at any speed as long as motor rpms were below 2500. Now I can feel it too. He advised STP fuel injector cleaner at a high concentrate and blow it out on the freeway. After doing just that with no change in ride. After that he felt a clogged injector or failing injector was the problem. I bought two injectors and he put them in, no change, he moved them and still no change.
    **Please note that during all this I have no engine code.
    He also replaced the TPS, no fix. Another mechanic felt that one of the coils might be breaking down. I bought one and put it in and test drove it in all 8 positions, no fix.

    To date, the symptoms and attempted fixes have been as follows:
    First felt vibration at 35-45 mph
    Started feeling it more, went to dealer.
    Drove a week and began to feel more noticeably.
    After fuel injector cleaner, no fix.

    First Diagnostic:
    Transmission fluids slightly dirty, had them change it.
    Old worn plugs, changed myself with exact replacements and proper gap settings (0.40).
    Tires out of balance, Balanced them.
    Flash Updates for ECM and TCM, updated them.
    Went home $450 lighter, still not fixed.

    Second Diagnostic:
    Torque Converter slipping during interlock. Both stated by dealer and first tranny shop.
    or possible bad TCM (no codes)

    Third Diagnostic:
    not torque converter.
    Clogged injector, ran truck hard with double dose of STP, no fix.
    Bought 2 injectors and moved them around, no fix.

    Fourth Diagnostic:
    Possible bad or faulty coil, bought one and played ring around the motor, no fix.

    Fifth Diagnostic:
    Trustworthy Tranny shop states no way it can be torque converter, says it must be tires. With truck off ground and wheels dangling, truck shook on lift, just like on road??

    Sixth Diagnostic:
    New Shop can't find any problem, then suggest rear diff service.
    Finds broken clutch plate and rebuilds. $850
    Problem unchanged and now shop says it is the tires.
    Buy new tires, $650, balance two times and road force balance one time and problems still there.

    After all of the above (over $2000) and hours and hours (priceless) of driving and thinking it feels like an out of round tire. A 35-50mph feels like a slight wobble or hop (tires are good and true and no bent rims) in the rear of the truck.

    Please help!!!!!
    Currently I'm out over $2000 and slightly better than started but not completely gone.
    No OBD codes.

    Could this be a driveshaft bent? Feels to slow and wobbly, not high speed vibration.

    Thanks for your help,
This discussion has been closed.